Screen stretching structure



May 7, 1940."

G. A. OVERSTROM El AL SCREEN STRETCHING STRUCTURE Filed Feb. 11, 1939 Gusfa Va A flv rahvm (40 Pg e Ovensfnom Co n md Ova sfrom INVENTOR5.

BY &9 ab 4 A TTORNE YS.

Patented May 7, 1940 SCREEN STRETCHING. STRUCTURE I I ..Gustave A. overstrom and George Overstrom, Eagle Rock, and Conrad OVerstrom, Pasadena,

Calif.

.Application February 11, 1939, Serial No. 255,906

.This invention involves an improved form of structure by means of which a screen cloth or wire screen such as is mounted in the box of vibrating screens, sorting and grading devices =1 and the like, may be secured therein and properly .tensioned. i Another object of this invention is to provide a structure by means of which the screen cloth or wire screen may be uniformly tensioned by the 10 uniformapplicationof pressure along the side edges and in the plane thereof.

A still further object of the invention is the provision of a mechanism of thistype so constructed and arranged for cooperation with the screen clothas to minimize the wear thereon.

Another object of the-invention is to provide a screen stretching and mounting device which .may be used in connection with screens, whether of wire, cloth or the like, which have no binding along the. side edges thereof.

Other objects of the invention will be apparent from the following detailed description and the embodiment thereofset' forth in the drawing by way of illustration; 7 v This inventionresides substantially in the com bination, construction, arrangement and relative location of parts, all in accordance with the following disclosure.

In the accompanying drawing,

: Figure 1 is a vertical, longitudinal section of v the screen box of a vibrating screen, omitting details not connected with the invention for the sake of simplicity.

Figure 2 is a vertical, transverse, cross-sectional view through the screen box of the vibrating screen and taken along lines Il of Figure 1.

Figure 3 is an enlarged detail of the same cross-section of Figure 2 with some parts broken away showing the stretching apparatus in its ini- 40 tial position before transverse stretching of the cloth is efiected.

Figure 4 is a cross-sectional view similar to Figure 3 of one side only of the screen box showing the position of the parts when the cloth is stretched. p

The nature, scope and operation of the invention will be more readily understood by first'describing the structural form employed in the drawing for the purpose of illustrating the invention.

The members I and 2 are sidemembers for the screen box. In an actual vibrating screen they will form the longitudinal sides of the'screen box and will be separated and spaced apart from each other a distance equal to the width thereof.

Extending transversely, across the screen box',

between the side members, are cross braces or bars, which may be, 'forexample, angleironssand Ts.. One of these'cross braces, a T, 3, appears in the drawing. readily appreciate, the nur'nber' and arrangement of'cross braces will be varieddepending upon th requirements of the structure. J Extending longitudinally along the side meme hers I and 2, on the-inner faces thereof, are i=0 angle irons or bars 4 which are securedto the side members in any suitable way, as. for example by bolting or welding in the. case of metals.

g Spaced above the angle irons 4 at a suitable distance are a pair of smaller angle irons'iavhlch 15 extend paralleltheretoand are secured also :to

the inner faces of the side members I and 2 in anysuitable manner. At 6 is the screen cloth made of any materials commonly 'usedfor this purpose, whichrestsupon the rubber supports g9 !5 in turn mounted on the longitudinally extending bars M which are T-shaped in crosssection and at its sideedges on the angleirons l.

Extending parallel; to the inner faces of theside plates I and 2, area pair of channel members] 25 formed as shown with flanges along each side edge; The upper flange lies above a longitudinal ledge 8 or thelike which also extends along the inner faces of the side plates l and 2 and are secured thereto in any suitable manner. I The lower flanges of the channel members I are encased in a. covering 9 of any suitable material such as, for example, strips of oak tanned leather. The leather strips are secured to the flanges in any suitable way such as by rivets, cementing, and the like.

At suitable intervals along the length. of the channel members I are bolts. H] which extend through openings in the side plates defined by suitably shapedsleeves l2 having the-seats l3 upon whichthe nuts ll engage when threaded to the bolts. If preferred, these nuts may be pro vided with integral handles thereby eliminating the necessity of using wrenches.

The screen 6 is putin place in the box formed 45, in part by the side members I and 2 in a: position such as is shown,'for example, in the drawing. The channel members 'I are then put in place so that the lower protected flange rests on the screen cloth adjacent the spaces betweenthe 5 towards the innerfaces of the side plates I and 2. 55

As those skilled in the artwill tially throughout the length of the side edges of the screen, it is apparent that. the cloth may be very uniformly tensioned in a transverse direction. Of course a series of tensioning bolts l0 may be distributed longitudinally along the said channels to give a greater degree of control over the tension suppliedi to the cloth and its distribution therein.

The members l2 through which the tensioning bolts I0 pass .must be provided with ample clearances so-that bolts Hi will not bind when tension is applied to the cloth. Sockets l3 provide an effective surface against which the nut ll presses.

.As the cloth is tensioned it rests firmly on the rubber supporting strips l5." These rubber strips are held in place .by members It whose holding surface'is preferably made dovetail to prevent the rubber from creeping outof place. The dovetail strips are fastened to T members l4, by weldingfor example. Members I4 also act as effective longitudinal ties or braces for the screen It nowbecomes readily apparent that the details of this invention may be applied to all forms of structures wherein flexible screen members and the like are tobe secured in place and/or tensioned. The exact construction of the various parts as illustrated by way of example may be readily varied by those skilled in the art without departing from the true and novel scope of the subject matterherein disclosed. We do not, therefore, desire to be strictly limited to'the disclosure as given for purposes of illustration, but rather to the claims granted us. What'is claimed is '1. In a screen mounting structure the combination "comprising a screen box having side frame members, a pair of spaced bars secured to the innerfaces of said members,'a screen cloth extending between said bars, and means pivoting on said side frame member for forcing the free-side edges of the screen cloth in planes parallel to the cloth between said bars to stretch the screen cloth.

2. In a device of the type described the combination including the side frame members of a screen box, a pair of vertically spaced bars secured to the inner faces of said members, and extending substantially throughout the length thereof, a screen cloth, channel members resting along the terminal edge of one channel leg against the inner faces of said side frame members, and movable into said spaces, and means for effecting such movement, the side edges of the screen cloth being squeezed between said pair of bars and said adjacent channel leg during movement of the cloth into the channel members.

3. A screen tensioning mechanism consisting of a pair of parallel side members provided with channels on their inner faces, said channels facing towards each other,a screen cloth extending between said channels, and means having cloth engaging portions which the side edges of the cloth overlap for wedging the cloth into said channels in contact with both channel walls whereby the cloth is, tensioned.

4:. A screen tensioning mechanism consisting of a pair of parallel side members having channels on their inner faces, said channels facing towards each other, a screen cloth extending between said channels and being folded back to engage both channel walls, and means for forcing the side edges of the cloth into said channels whereby the screen cloth is tensioned, said means including resilient strips engaging the clothin the trough formed by folding and'together forming a snug fit in said channels.

5. In a vibrating screen cloth tensioning mechanism, the combination including the side frame members of a screen box, pairs of parallel bars on the inner faces of said members and forming elongated channels facing each other, the lowermost bar of each pair being transversely wider than the uppermost bar, ascreen cloth extending between said bars, and tensioning means including flanged members engageable with the side frame members along one side and with the side edges of said cloth for forcing them between the pairs of bars in contact with the'opposed faces thereof to tension the cloth and lock it in that 

